Manufacture of crystallized abrasives.



a molten 8 PA w moms a. ALLEN, or rononro, onra'mo, CANADA, assrenon To GENERAL asnasrvr. comrm, me, or NIAGARA rams, new roar.

-mmuraorn or cnssrannrzan an .5

York Pi-oceof' Ontario, Canada, have invented certain new and useful Improve:

merits in the Manufacture of Crystallized Abrasives, of which the following is a specification.

llhis invention fusion of anhydrj us "or hydrated oxid' of to the solid state, ground and made up by combination with a suitable magma. into grindingiwheels, or other forms of abrasive tciols. The requirements in such abrasive are'that they may be'obtained possessing varying physical properties such as difes' of hardness and toughness, and that it shall-always be possible to ex-- fevent idegre actly duplicatej'tools-of any given physical properties; I have found'that the hardness of the tool depends largely on the alumina ,content', but thetoughne'ss or" -.temper 1S largely dependent on the crystallization of the alumina. i L I have in United States Patent No.

1,1-87,225, discloseda method by which the character of the crystallization mayto a certain extent be 0011 trolled, namely, by controlling the rate or cooling, the specific means suggested being the varying of the size of the molds employed. [1 have now discovered as the result of experiment that furthercon'trol of, the crystallization can be obtained by heating the molds or-luggies into which the molten material is poured to varying temperatures, as the higher the tem-. perature of the luggie at .theltime of pouring'the slower will be the rate of cooling, other conditions being equal.- 1 have fur ther discovered that ,the temperature of the molten material at the time of pouring has an unexpected effect on the nature of the crystallization. If, for example, the temperature of the molten material, be very high, the resultant product isof a very brittle'nature, whereas if the temperature is only, slightly above the melting pointa' very obtained. hese' charactherefore I control both the temperature of g'odu'ct and-the. rate of cooling,

relates particularly to the production of alu inous'abrasives by the be mod-ified by the 1y also. heat the luggies into IVES.

which the material is poured to assist in the control of the cooling and to prevent any sudden chilling of any part of the material poured.

.ln' carrying out my process the bauxite or any other form of'alumina which may be ndeed with a suitable tap hole or tap'holes. :lhe temperature is controlled by regulatlug-the height of the electrodes or by regulating the current, or .in any other suitable way. Ordinarily the temperature canrwith suflicient accuracy be so regulated without the use of a pyrometer, though such may be employed if desired. Whenthe necessary temperature of the fused product is reached, it IS tapped into luggies, preferably of metal and preferab'ly of such size as to cause the cooling to take place at the desired rate, the size ofthe luggies being. varied to suit the rate pf cooling desired. These luggies are previously heated'to a greater or lesse'rdegree to control the rate of cooling of the fused product and to prevent chilling of any. portions of the fused material poured. -By proceeding in the manner described, I am enabled to secure in the final product the physical properties desired as set out in the preamble to this specification;

What Iclaim as my invention is 1. A process of treating aluminous abra sives which consists in fusing alumina in an electric furnace, in controlling the temperature of the molten material according to the crystalline characteristics desired in the resultant product, and subsequently pouring and cooling the molten material.

.' 2. A process of treatin aluminous abrasives which consists in fusing alumina in an electric furnace, in controlling the temperature of the molten material according to the crystalline characteristics desired in the resultant product, and subsequently pouring the molten inate'rial intopre-heated molds.

3. A process of treating aluminous abrasives which consists in fusing alumina in an electric furnace, in controlling the temperature of the molten material according to the crystalline characteristics desired intheresultant product, and subsequently pouring the molten material and controlling-its rate of cooling according to the crystalline characteristics desired in theresultant product. j 4. A- process of treating aluminous ,abrasives which-consistsin'fusing alumina in an employed is fused in an electric furnace proioo ture o'f'the molten material according to. thc

' crystalline characteristics desired in thc're sultant product, and subsequently fouling tliel molten material into pre-heate molds and. controlling. its rate of cooling according 'to the crystalline characteristics desired-in the resultant product. v

5. A process of treating aluminousabrasives which consists in fusing alumina in an electric furnace and pouring the ssme into pro-heated molds.

' 6; A' process oftreatin'g ,alumi'lious 'abra-' sives which consists in fusing-alumna in an electric furnace and pouring the same into pre-heated molds and thereafter controlling its rate of cooling according to the crystalline characteristics desired in thelresul'tan't product. I

7. A process of treating aluminous abrasives which consists in fusing alumina in an electric furnace and pouring the same into molds and thereafter controlling its rate of cool ng according to the crystalline characrodu'ct. this 18th teristics desired m-the resultant Signed at Niagara- Falls, N. day of July1916.

T-HOMA S B. ALLEN. Witnesses:

P ELHAMBLY,

MAoDE-B. HAMBLY. 

